1. Field of the Invention
This invention relates, generally, to building construction. More particularly, it relates to a modular roof panel construction where the slope of the roof is built into the panel.
2. Description of the Prior Art
Expanded polystyrene (EPS) is used extensively in the construction industry because it is light in weight yet strong and inexpensive. For example, its closest competitor, urethane foam, costs about three times as much.
EPS is also desirable because it can be cut into different shapes with some ease. Architects often specify its use when placing decorative columns or other designs on the facade of a building. More commonly, however, it is used in roof construction or as a supplemental roof known as a roofover.
Since EPS is quite brittle, however, it is covered with a thin metallic skin if it is being used not as a decoration but as a working part of a structure. A suitable adhesive is employed to bond the skin to the EPS core.
In the roofing industry, EPS panels are often used to overlie existing roofs to enhance the insulation of the space below the roof and to seal the roof against leakage. Typically, EPS roofing panels are of modular construction so that a plurality of panels may be combined to form a monolithic roof. Numerous patents have been awarded on interlocking means that facilitate the quick and easy joinder of individual panels, that prevent leakage of moisture through the seams, and so on.
All of the EPS roofing panels of the prior art share a common feature: uniform thickness. Regardless of the size of the panel, the type of interlocking means employed, whether a metal skin is used on one or two sides thereof, etc., the thickness of the panel is always uniform along the extent and breadth thereof.
Thus, all EPS roof panels heretofore known cause the same problems in the roof construction industry that are caused by the other materials used in the industry. To properly slope a roof, either a truss or other support surface having the desired slope must be built to support the roof atop walls having a common height, or the walls of the structure must be built to accommodate the slope.
When the latter technique is employed, no two of the wall sections will have the same configuration. More particularly, each wall section will have a slope built into its top edge, and that slope must match the slope of the contiguous wall sections.
Thus, the ceiling of the structure being provided with such a roof will be lower at its outermost edge than at its innermost edge, i.e., the downward slope of the roof translates into a downward slope of the interior ceiling of the space being roofed. Thus, the occupants of the space lose headroom as they approach the outer wall of the structure.
Moreover, a structure with such a roof is less appealing aesthetically than is a structure where the end walls have a common height.
If an EPS roof panel construction could be discovered that would enable add on rooms, for example, to have pitched roofs but unpitched ceilings, such a panel would revolutionize the construction industry.
No EPS roof panel construction of the prior art teaches or suggests how such a leap in construction industry technology could be accomplished.
In the urethane panel construction industry, U.S. Pat. No. 3,792,141 to Offutt shows what is called a "roof structure" that has a built in pitched roof and a flat bottom; however, it is well known in the urethane industry that urethane foam expands with enormous force as it cures, and that, consequently, large masses are required to mold urethane items of large sizes. Thus, the construction of a urethane panel large enough to form a part of a modular roof is not believed to be within the realm of practicality. Perhaps even more importantly, the Offutt construction teaches away from modular panels having edge-to-edge interlocking means.
When the prior art is viewed as a whole and in its entirety, the vast scope and content of such art suggests, at most, continued evolutionary change; a breakthrough-type development in this art would not have been obvious to one of ordinary skill in this art at the time this invention was made.